Thirty million words: That is the size of the “word gap,” the number of extra words, so to speak, that children of affluent parents hear from their parents during toddlerhood that poor children don’t hear from theirs.

The word gap has been found to have serious consequences once children start school. As a recent headline in The Atlantic put it, “Poor Kids Are Starving for Words.” This issue was the focus at a recent White Houseconference, calling for people to address the word gap with the same passion they do child hunger.

There’s been a turn in the road on the topic, too: A new study released at the conference found that it’s quality, not just quantity, that matters.

“It’s not just about shoving words in,” said Kathryn Hirsh-Pasek, a professor of psychology at Temple University and lead author of the study, as quoted in The New York Times. “It’s about having these fluid conversations around shared rituals and objects.... That is the stuff from which language is made.”

Efforts to bridge “the gap” include, obviously, encouraging parents to talk with their children and also making parents understand the power of their own conversation.

The Atlantic noted, “One study found that low-income parents underestimate their power to influence their children’s cognitive development, sometimes by as much as 50 percent.”

Providence Talks, in Rhode Island, outfits children with devices that record the number of words they hear each day. I couldn’t find any pictures, but it sounds rather like outfitting baby elk in the forest with radio collars.

The 30 million figure, by the way, goes back to a study by Betty Hart and Todd R. Risley, published in 1995 as “Meaningful Differences in the Everyday Experience of Young American Children.”

The online commentariat has pushed back. A mother in Louisville crunched the numbers and found that the 30 million breaks down to 32.6 extra words per waking minute of a child’s first three years. (You can do the math, too; assume 14 waking hours per day.)

Who can spend that much time talking to their kids? And wouldn’t such parental verbosity make it hard for Baby to get even a gurgle, let alone a word, in edgewise?

Issue was taken as well with the idea that “parentese” fosters language ability. The Times again: “[R]esearchers who observed 11- and 14-month-old children in their homes found that the prevalence of one-on-one interactions and frequent use of parentese – the slow, high-pitched voice commonly used for talking to babies – were reliable predictors of language ability at age 2.”

A number of commenting parents insisted they always spoke to their own young children in grown-up tones. There may be a little selective memory here; maybe if we had radio collars on these people, too, we’d know for sure.

If there’s an encouraging message here, though, it’s that talk may be cheap, but the power of language is priceless.